R50.9 — Fever, unspecified
Is R50.9 billable?
Yes, but R50.9 is an unspecified code. R50.9 is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, R50.9 is an unspecified or catch-all code. Payers apply additional scrutiny to unspecified codes and many deny them when the medical record supports a more specific option, so check the documentation before selecting R50.9 — the more specific alternatives are listed below.
More specific alternatives
R50.9 at a glance
| Code | R50.9 |
|---|---|
| Description | Fever, unspecified |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does R50.9 group to?
R50.9 sits in MDC 18 and helps define the logic of 1 MS-DRG (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 864Fever and Inflammatory Conditionsmedical
How is R50.9 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to R50.9. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)
- FUO (fever of unknown origin)
- Hyperpyrexia
- PUO (pyrexia of unknown origin)
- Pyrexia (of unknown origin)
- Chill › with fever (s)
- Elevated, elevation › body temperature
- Fever › ephemeral (inanition) (of unknown origin) (persistent) (with chills) (with rigor)
- Fever › persistent (inanition) (of unknown origin) (persistent) (with chills) (with rigor)
- Fever › unknown origin (inanition) (of unknown origin) (persistent) (with chills) (with rigor)
- High › temperature
- Hyperpyrexia › unknown origin
Inclusion terms
Alternative wording in documentation that is classified to R50.9.
- Fever NOS
- Fever of unknown origin [FUO]
- Fever with chills
- Fever with rigors
- Hyperpyrexia NOS
- Persistent fever
- Pyrexia NOS
Excludes1 — never code together — inherited from R50
The conditions below can never be reported together with R50.9 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Excludes2 — not included here — inherited from Chapter 18
The conditions below are not part of R50.9, but a patient may have both at the same time. When documentation supports it, R50.9 and the excluded code may both be reported.
How long has R50.9 existed?
R50.9 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.